Bacteriophages have been isolated that infect all of the Bacteroides subspecies listed in the 8th edition of Bergeys Manual (p. 387). These subspecies have been elevated to species rank. The species or unnamed DNA homology groups on which the phages have been isolated include B. fragilis (55 isolates), B. thetaiotaomicron (3 isolates), B. vulgatus (4 isolates), B. distasonis (2 isolates), B. uniformis (3 isolates), B. ovatus (2 isolates), "3452-A" (1 isolate), and B. eggerthii (1 isolate). Research will include experiments on: the biology of the phages which will include morphological, serological, latent period and burst size studies. The nucleotide sequence similarities of the DNA preparations from the phages will be compared with each other and with preparations of host DNA and host plasmid DNA. A phage typing system for the rapid identification of the clinically important species will be completed and tested on newly acquired clinical isolates. The apparent carrier or pseudolysogenic organisms will be further studied. The search for lysogenic phages will continue. Any phages will be used to attempt transduction of those phenotypic characteristics that are variable among our bacterial cultures including auxotrophic and drug resistant mutations.